JP7432036B2 - Electronic devices, control methods for electronic devices, and programs - Google Patents

Description

The present disclosure relates to an electronic device, a method of controlling the electronic device, and a program.

For example, in fields such as automobile-related industries, technology for measuring the distance between one's own vehicle and a predetermined object is considered important. In particular, in recent years, radar (RADAR (Radio Detecting and Ranging)), which measures the distance between objects and other objects by transmitting radio waves such as millimeter waves and receiving reflected waves from objects such as obstacles, has been introduced. Various technologies are being researched. The importance of technology for measuring distances and other distances will continue to grow as technology to assist drivers in driving and technology related to automated driving that automates part or all of driving is expected to increase. is expected.

Furthermore, various proposals have been made regarding techniques for detecting the presence of a predetermined object by receiving a reflected wave of a transmitted radio wave reflected by the object. For example, Patent Document 1 discloses a device that suppresses clutter by storing past reflected wave data as a map. Further, Patent Document 2 discloses a radar device that distinguishes a plurality of targets into moving objects and stationary objects and measures the distance and speed of each object.

Japanese Patent Publication No. 60-093975 Japanese Patent Application Publication No. 2000-180536

In a technology such as the above-mentioned radar, it is desirable that an object can be detected well by receiving a reflected wave of a transmitted wave reflected by a predetermined object.

An object of the present disclosure is to provide an electronic device, a control method for the electronic device, and a program that can detect objects well.

An electronic device according to an embodiment includes:
An electronic device stationary relative to the ground that detects an object based on a transmission wave transmitted from a transmission antenna and a reflected wave from the transmission wave reflected by the object,
From the reflected wave,
Regarding the first area that is stationary with respect to the ground, the signal intensity corresponding to the distance of the first area and the pre-calculated distance of the area of the stationary object that is stationary with respect to the ground Detecting an object in the first region based on the difference with the corresponding signal strength,
For the second area that is not stationary with respect to the ground, the signal intensity corresponding to the distance of the second area and the pre-calculated distance of the area of the stationary object that is stationary with respect to the ground. The object in the second region is detected without calculating the difference between the signal intensity and the signal intensity corresponding to the second region .

A method for controlling an electronic device according to an embodiment includes:
A method for controlling electronic equipment that is stationary with respect to the ground,
The method includes the step of detecting the object based on a transmission wave transmitted from a transmission antenna and a reflected wave resulting from the transmission wave being reflected by the object.
The detecting step includes:
From the reflected wave,
Regarding the first area that is stationary with respect to the ground, the signal intensity corresponding to the distance of the first area and the pre-calculated distance of the area of the stationary object that is stationary with respect to the ground Detecting an object in the first region based on the difference with the corresponding signal strength,
For the second area that is not stationary with respect to the ground, the signal intensity corresponding to the distance of the second area and the pre-calculated distance of the area of the stationary object that is stationary with respect to the ground. The object in the second region is detected without calculating the difference between the signal intensity and the signal intensity corresponding to the second region .

The program according to one embodiment is
For electronic devices that are stationary relative to the ground,
A step of detecting the object is performed based on a transmission wave transmitted from a transmission antenna and a reflected wave resulting from the transmission wave being reflected by the object.
The detecting step includes:
From the reflected wave,
Regarding the first area that is stationary with respect to the ground, the signal intensity corresponding to the distance of the first area and the pre-calculated distance of the area of the stationary object that is stationary with respect to the ground Detecting an object in the first region based on the difference with the corresponding signal strength,
For the second area that is not stationary with respect to the ground, the signal intensity corresponding to the distance of the second area and the pre-calculated distance of the area of the stationary object that is stationary with respect to the ground. The object in the second region is detected without calculating the difference between the signal intensity and the signal intensity corresponding to the second region .

According to one embodiment, it is possible to provide an electronic device, a method for controlling the electronic device, and a program that can effectively detect objects.

FIG. 2 is a diagram illustrating how an electronic device is used according to an embodiment. FIG. 1 is a functional block diagram schematically showing the configuration of an electronic device according to an embodiment. FIG. 1 is a functional block diagram showing part of the configuration of an electronic device according to an embodiment. FIG. 2 is a diagram illustrating a configuration of a transmission signal according to an embodiment. 3 is a flowchart illustrating the operation of an electronic device according to an embodiment. FIG. 6 is a diagram illustrating a comparative example illustrating processing results in a control unit according to an embodiment. FIG. 3 is a diagram illustrating an example of a processing result in a control unit according to an embodiment.

Hereinafter, one embodiment will be described in detail with reference to the drawings.

For example, by being attached to a stationary structure (stationary object), the electronic device according to one embodiment can detect a predetermined object existing around the stationary object. Here, the stationary object may be any device such as a traffic light or roadside device installed at an intersection, or any location such as an indoor floor, wall, or ceiling. For this reason, the electronic device according to one embodiment can transmit transmission waves around the stationary object from a transmission antenna installed on the stationary object. Further, the electronic device according to one embodiment can receive reflected waves obtained by reflecting transmitted waves from a receiving antenna installed on a stationary object. At least one of the transmitting antenna and the receiving antenna may be included in, for example, a radar sensor installed on a stationary object.

Hereinafter, as a typical example, a configuration in which an electronic device according to an embodiment is attached to a stationary structure will be described. Here, what the electronic device according to one embodiment detects may be, for example, a car or the like existing around the electronic device attached to a stationary object. What the electronic device according to one embodiment detects is not limited to automobiles. The electronic device according to one embodiment detects self-driving cars, buses, trucks, motorcycles, bicycles, ships, aircraft, agricultural equipment such as tractors, snowplows, cleaning trucks, police cars, ambulances, fire engines, helicopters, It may be a variety of objects, such as a drone or a drone. The electronic device according to one embodiment can measure the distance between the electronic device and the object in a situation where the objects around the electronic device attached to a stationary object may move. Further, the electronic device according to one embodiment can measure the distance between the electronic device and the object even if both the electronic device and the object are stationary.

First, an example of object detection by an electronic device according to an embodiment will be described.

FIG. 1 is a diagram illustrating how an electronic device is used according to an embodiment. FIG. 1 shows an example in which an electronic device having a sensor function including a transmitting antenna and a receiving antenna according to an embodiment is installed on a stationary object.

In a stationary object 100 shown in FIG. 1, an electronic device 1 having a function as a sensor including a transmitting antenna and a receiving antenna according to an embodiment is installed. Moreover, the stationary object 100 shown in FIG. 1 may have the electronic device 1 according to an embodiment built therein, for example. The specific configuration of the electronic device 1 will be described later. The electronic device 1 may include, for example, at least one of a transmitting antenna and a receiving antenna. Further, the electronic device 1 may include at least one of other functional units, such as at least a part of the control unit 10 (FIG. 2) included in the electronic device 1, as appropriate. Further, in the electronic device 1, at least one of other functional units, such as at least a part of the control unit 10 (FIG. 2) included in the electronic device 1, may be installed outside the electronic device 1. The stationary object 100 shown in FIG. 1 may be a structure such as a traffic light or a roadside device installed at an intersection, but may be any type of structure. In FIG. 1, a stationary object 100 may remain stationary without moving.

As shown in FIG. 1, an electronic device 1 including a transmitting antenna is installed on a stationary object 100. In the example shown in FIG. 1, only one electronic device 1 including a transmitting antenna and a receiving antenna is installed toward the Y-axis positive direction of the stationary object 100. Here, the position where the electronic device 1 is installed on the stationary object 100 is not limited to the position shown in FIG. 1, and may be set at another position as appropriate. Further, the number of such electronic devices 1 may be one or more, depending on various conditions (or requirements) such as the measurement range and/or accuracy of the stationary object 100.

The electronic device 1 transmits electromagnetic waves as transmission waves from a transmission antenna, as described later. For example, when a predetermined object (for example, the object 200 shown in FIG. 1) exists around the stationary object 100, at least a portion of the transmission wave transmitted from the electronic device 1 is reflected by the object and becomes a reflected wave. Then, by receiving such a reflected wave by, for example, a receiving antenna of the electronic device 1, the electronic device 1 attached to the stationary object 100 can detect the object as a target.

The electronic device 1 including the transmitting antenna may typically be a RADAR (Radio Detecting and Ranging) sensor that transmits and receives radio waves. However, the electronic device 1 is not limited to a radar sensor. The electronic device 1 according to one embodiment may be, for example, a sensor based on LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) technology using light waves. Sensors such as these can be configured to include, for example, a patch antenna. Since technologies such as RADAR and LIDAR are already known, detailed descriptions may be simplified or omitted as appropriate.

An electronic device 1 attached to a stationary object 100 shown in FIG. 1 receives from a receiving antenna a reflected wave of a transmission wave transmitted from a transmitting antenna. In this way, the electronic device 1 can detect the predetermined object 200 existing within a predetermined distance from the stationary object 100 as a target. For example, as shown in FIG. 1, the electronic device 1 can measure the distance L between a stationary object 100 and a predetermined object 200. Furthermore, the electronic device 1 can also measure the relative velocity between the stationary object 100 and the predetermined object 200. Furthermore, the electronic device 1 can also measure the direction (angle of arrival θ) in which the reflected wave from the predetermined object 200 arrives at the stationary object 100.

Here, the object 200 may be, for example, a car that runs around the stationary object 100. The objects 200 include humans such as motorcycles, bicycles, strollers, and pedestrians, animals, insects, and other living organisms, guardrails, median strips, road signs, steps on sidewalks, walls, manholes, houses, buildings, bridges, etc. It may be any object existing around the stationary object 100, such as a building or an obstacle. Furthermore, the object 200 may be moving, stopped, or stationary. For example, the object 200 may be a car parked or stopped around the stationary object 100. The objects 200 are not limited to those on the roadway, but also include sidewalks, farms, farmland, parking lots, vacant lots, spaces on roads, inside stores, crosswalks, on water, in the air, in gutters, rivers, and in other moving objects. It may be located at an appropriate location, such as inside or outside a building or other structure. In the present disclosure, objects detected by the electronic device 1 include not only inanimate objects but also living things such as humans, dogs, cats, horses, and other animals. Objects detected by the electronic device 1 of the present disclosure include targets including people, objects, animals, etc. that are detected by radar technology.

In FIG. 1, the ratio between the size of electronic device 1 and the size of stationary object 100 does not necessarily represent the actual ratio. Further, in FIG. 1 , the electronic device 1 is shown installed outside a stationary object 100 . However, in one embodiment, the electronic device 1 may be installed at various positions on the stationary object 100. For example, in one embodiment, the electronic device 1 may be installed inside the stationary object 100 so that it does not appear on the outside of the stationary object 100.

Hereinafter, as a typical example, the transmitting antenna of the electronic device 1 will be described as one that transmits radio waves in a frequency band such as millimeter waves (30 GHz or higher) or sub-millimeter waves (for example, around 20 GHz to 30 GHz). For example, the transmitting antenna of the electronic device 1 may transmit radio waves having a frequency bandwidth of 4 GHz, such as 77 GHz to 81 GHz.

FIG. 2 is a functional block diagram schematically showing a configuration example of the electronic device 1 according to an embodiment. Further, FIG. 3 is a functional block diagram showing the control unit 10 of the electronic device 1 shown in FIG. 2 in more detail. An example of the configuration of the electronic device 1 according to one embodiment will be described below.

When measuring distance or the like using a millimeter wave radar, a frequency modulated continuous wave radar (hereinafter referred to as FMCW radar) is often used. The FMCW radar generates a transmission signal by sweeping the frequency of radio waves to be transmitted. Therefore, for example, in a millimeter wave type FMCW radar that uses radio waves in the 79 GHz frequency band, the frequency of the radio waves used has a frequency bandwidth of 4 GHz, such as 77 GHz to 81 GHz. Radar in the 79 GHz frequency band is characterized by a wider usable frequency bandwidth than other millimeter wave/sub-millimeter wave radars in the 24 GHz, 60 GHz, and 76 GHz frequency bands, for example. Hereinafter, such an embodiment will be described as an example. The FMCW radar radar method used in the present disclosure may include an FCM method (Fast-Chirp Modulation) that transmits a chirp signal at a shorter period than usual. The signal generated by the signal generation unit 21 is not limited to an FM-CW signal. The signal generated by the signal generation unit 21 may be a signal of various systems other than the FM-CW system. The transmission signal sequence stored in an arbitrary storage unit may be different depending on these various methods. For example, in the case of the above-mentioned FM-CW radar signal, a signal whose frequency increases and a signal whose frequency decreases for each time sample may be used. Since known techniques can be appropriately applied to the various methods described above, a more detailed explanation will be omitted.

As shown in FIG. 2, the electronic device 1 according to one embodiment includes a control section 10. Further, the electronic device 1 according to one embodiment may appropriately include other functional units such as the transmitter 20 and at least one of the receivers 30A to 30D. As shown in FIG. 2, the electronic device 1 may include a plurality of receiving sections, such as receiving sections 30A to 30D. Hereinafter, when the receiving section 30A, the receiving section 30B, the receiving section 30C, and the receiving section 30D are not distinguished from each other, they will simply be referred to as "the receiving section 30."

As shown in FIG. 3, the control unit 10 includes a distance FFT processing unit 11, a velocity FFT processing unit 12, a difference calculation unit 13, a storage unit 14, an update processing unit 15, a determination unit 16, an angle of arrival estimation unit 17, and an object The detection unit 18 may be included. These functional units included in the control unit 10 will be further described later.

As shown in FIG. 2, the transmitter 20 may include a signal generator 21, a synthesizer 22, phase controllers 23A and 23B, amplifiers 24A and 24B, and transmit antennas 25A and 25B. Hereinafter, when the phase control section 23A and the phase control section 23B are not distinguished, they will simply be referred to as "phase control section 23." Further, hereinafter, when the amplifier 24A and the amplifier 24B are not distinguished from each other, they will simply be referred to as "amplifier 24." Further, hereinafter, when the transmitting antenna 25A and the transmitting antenna 25B are not distinguished, they will simply be referred to as "transmitting antenna 25."

As shown in FIG. 2, the receiving section 30 may include corresponding receiving antennas 31A to 31D. Hereinafter, when the receiving antenna 31A, the receiving antenna 31B, the receiving antenna 31C, and the receiving antenna 31D are not distinguished from each other, they will simply be referred to as "receiving antenna 31." Further, each of the plurality of reception sections 30 may include an LNA 32, a mixer 33, an IF section 34, and an AD conversion section 35, as shown in FIG. The receiving units 30A to 30D may each have a similar configuration. In FIG. 2, the configuration of only the receiving section 30A is schematically shown as a representative example.

The electronic device 1 described above may include, for example, a transmitting antenna 25 and a receiving antenna 31. Further, the electronic device 1 may include at least one of other functional units such as the control unit 10 as appropriate.

The control unit 10 included in the electronic device 1 according to one embodiment can control the operation of the electronic device 1 as a whole, as well as control each functional section that constitutes the electronic device 1. In one embodiment, the control unit 10 may have a function of performing various signal processing on the received signal received by the receiving unit 30 as a reflected wave. Control unit 10 may include at least one processor, such as a CPU (Central Processing Unit), to provide control and processing capabilities to perform various functions. The control unit 10 may be implemented by a single processor, several processors, or individual processors. A processor may be implemented as a single integrated circuit. An integrated circuit is also called an IC (Integrated Circuit). A processor may be implemented as a plurality of communicatively connected integrated and discrete circuits. The processor may be implemented based on various other known technologies. In one embodiment, the control unit 10 may be configured as, for example, a CPU and a program executed by the CPU. The control unit 10 may include a memory (any storage unit) necessary for the operation of the control unit 10 as appropriate.

Here, the arbitrary storage unit (memory necessary for the operation of the control unit 10) may store programs executed in the control unit 10, results of processes executed in the control unit 10, and the like. Furthermore, any storage unit may function as a work memory for the control unit 10. The arbitrary storage unit can be configured by, for example, a semiconductor memory or a magnetic disk, but is not limited to these, and can be any storage device. Further, for example, the arbitrary storage unit may be a storage medium such as a memory card inserted into the electronic device 1 according to the present embodiment. Further, the arbitrary storage unit may be the internal memory of the CPU used as the control unit 10, as described above.

In one embodiment, an arbitrary storage unit may store various parameters for setting a range in which an object is detected by the transmission wave T transmitted from the transmission antenna 25 and the reflected wave R received from the reception antenna 31.

In the electronic device 1 according to one embodiment, the control unit 10 can control at least one of the transmitting unit 20 and the receiving unit 30. In this case, the control unit 10 may control at least one of the transmitting unit 20 and the receiving unit 30 based on various information stored in an arbitrary storage unit. Furthermore, in the electronic device 1 according to one embodiment, the control unit 10 may instruct the signal generation unit 21 to generate a signal, or may control the signal generation unit 21 to generate a signal.

The signal generation unit 21 generates a signal (transmission signal) to be transmitted as a transmission wave T from the transmission antenna 25 under the control of the control unit 10. When generating the transmission signal, the signal generation section 21 may allocate the frequency of the transmission signal based on control by the control section 10, for example. Specifically, the signal generation unit 21 may allocate the frequency of the transmission signal according to parameters set by the control unit 10, for example. For example, the signal generation unit 21 generates a signal of a predetermined frequency in a frequency band such as 77 to 81 GHz by receiving frequency information from the control unit 10 or any storage unit. The signal generation section 21 may be configured to include a functional section such as a voltage controlled oscillator (VCO), for example.

The signal generation unit 21 may be configured as hardware having the relevant function, may be configured with a microcomputer, for example, or may be configured as a processor such as a CPU and a program executed by the processor. Good too. Each functional unit described below may be configured as hardware having the relevant function, or if possible, may be configured with a microcomputer, for example, or executed by a processor such as a CPU and the relevant processor. It may also be configured as a program, etc.

In the electronic device 1 according to one embodiment, the signal generation unit 21 may generate a transmission signal (transmission chirp signal) such as a chirp signal, for example. In particular, the signal generation unit 21 may generate a signal (linear chirp signal) whose frequency changes periodically and linearly. For example, the signal generation unit 21 may generate a chirp signal whose frequency increases periodically and linearly from 77 GHz to 81 GHz over time. Further, for example, the signal generation unit 21 may generate a signal whose frequency periodically repeats a linear increase (up chirp) and decrease (down chirp) from 77 GHz to 81 GHz over time. The signal generated by the signal generation section 21 may be set in advance in the control section 10, for example. Furthermore, the signal generated by the signal generation section 21 may be stored in advance in, for example, an arbitrary storage section. Since chirp signals used in technical fields such as radar are well known, a more detailed description will be simplified or omitted where appropriate. The signal generated by the signal generation section 21 is supplied to the synthesizer 22.

FIG. 4 is a diagram illustrating an example of a chirp signal generated by the signal generation unit 21.

In FIG. 4, the horizontal axis represents elapsed time, and the vertical axis represents frequency. In the example shown in FIG. 4, the signal generation unit 21 generates a linear chirp signal whose frequency changes periodically and linearly. In FIG. 4, each chirp signal is shown as c1, c2, . . . , c8. As shown in FIG. 4, the frequency of each chirp signal increases linearly over time.

In the example shown in FIG. 4, one subframe includes eight chirp signals such as c1, c2, . . . , c8. That is, subframe 1 and subframe 2 shown in FIG. 4 each include eight chirp signals such as c1, c2, . . . , c8. Furthermore, in the example shown in FIG. 4, 16 subframes such as subframe 1 to subframe 16 are included as one frame. That is, frame 1, frame 2, etc. shown in FIG. 4 each include 16 subframes. Further, as shown in FIG. 4, a frame interval of a predetermined length may be included between frames. One frame shown in FIG. 4 may have a length of, for example, about 30 to 50 milliseconds.

In FIG. 4, frames 2 and subsequent frames may have a similar configuration. Further, in FIG. 4, frames 3 and subsequent frames may have a similar configuration. In the electronic device 1 according to one embodiment, the signal generation unit 21 may generate the transmission signal as an arbitrary number of frames. Further, in FIG. 4, some chirp signals are omitted. In this way, the relationship between the time and frequency of the transmission signal generated by the signal generation section 21 may be stored in, for example, an arbitrary storage section.

In this way, the electronic device 1 according to one embodiment may transmit a transmission signal composed of subframes including a plurality of chirp signals. Further, the electronic device 1 according to one embodiment may transmit a transmission signal composed of a frame including a predetermined number of subframes.

Hereinafter, the electronic device 1 will be described as transmitting a transmission signal having a frame structure as shown in FIG. 4. However, the frame structure shown in FIG. 4 is just an example, and the number of chirp signals included in one subframe is not limited to eight, for example. In one embodiment, the signal generation unit 21 may generate subframes including an arbitrary number (for example, an arbitrary plurality) of chirp signals. Further, the subframe structure shown in FIG. 4 is also an example, and the number of subframes included in one frame is not limited to 16, for example. In one embodiment, the signal generation unit 21 may generate a frame including an arbitrary number (for example, an arbitrary plurality) of subframes. The signal generation unit 21 may generate signals of different frequencies. The signal generation unit 21 may generate a plurality of discrete signals having frequencies f and different bandwidths.

Returning to FIG. 2, the synthesizer 22 increases the frequency of the signal generated by the signal generation unit 21 to a frequency in a predetermined frequency band. The synthesizer 22 may increase the frequency of the signal generated by the signal generation unit 21 to the frequency selected as the frequency of the transmission wave T transmitted from the transmission antenna 25. The frequency selected as the frequency of the transmission wave T transmitted from the transmission antenna 25 may be set by the control unit 10, for example. Further, the frequency selected as the frequency of the transmission wave T transmitted from the transmission antenna 25 may be stored in, for example, an arbitrary storage unit. The signal whose frequency has been increased by the synthesizer 22 is supplied to the phase control section 23 and the mixer 33. When there are a plurality of phase control sections 23, the signal whose frequency has been increased by the synthesizer 22 may be supplied to each of the plurality of phase control sections 23. Further, when there are a plurality of receiving sections 30, the signal whose frequency has been increased by the synthesizer 22 may be supplied to each mixer 33 in the plurality of receiving sections 30.

The phase control section 23 controls the phase of the transmission signal supplied from the synthesizer 22. Specifically, the phase control unit 23 may adjust the phase of the transmission signal by appropriately advancing or delaying the phase of the signal supplied from the synthesizer 22 based on the control by the control unit 10, for example. In this case, the phase control unit 23 may adjust the phase of each transmission signal based on the path difference between each transmission wave T transmitted from the plurality of transmission antennas 25. By appropriately adjusting the phase of each transmission signal by the phase control unit 23, the transmission waves T transmitted from the plurality of transmission antennas 25 strengthen each other in a predetermined direction to form a beam (beam forming). In this case, the correlation between the direction of beamforming and the amount of phase to be controlled of the transmission signals transmitted by each of the plurality of transmission antennas 25 may be stored in, for example, an arbitrary storage unit. The transmission signal whose phase has been controlled by the phase control section 23 is supplied to the amplifier 24.

The amplifier 24 amplifies the power of the transmission signal supplied from the phase control section 23 based on control by the control section 10, for example. When the electronic device 1 includes a plurality of transmitting antennas 25, the plurality of amplifiers 24 control the power (electric power) of the transmission signal supplied from each corresponding one of the plurality of phase control sections 23, for example, by the control section 10. Each may be amplified based on. Since the technique itself for amplifying the power of a transmission signal is already known, a more detailed explanation will be omitted. Amplifier 24 is connected to transmitting antenna 25 .

The transmission antenna 25 outputs (transmits) the transmission signal amplified by the amplifier 24 as a transmission wave T. When the electronic device 1 includes a plurality of transmitting antennas 25, the plurality of transmitting antennas 25 may each output (transmit) a transmission signal amplified by a corresponding one of the plurality of amplifiers 24 as a transmission wave T. . Since the transmitting antenna 25 can be configured similarly to transmitting antennas used in known radar technology, a more detailed description will be omitted.

In this way, the electronic device 1 according to one embodiment includes the transmitting antenna 25 and can transmit a transmitting signal (for example, a transmitting chirp signal) as a transmitting wave T from the transmitting antenna 25. Here, at least one of the functional units constituting the electronic device 1 may be housed in one housing. Further, in this case, the one casing may have a structure that cannot be easily opened. For example, it is preferable that the transmitting antenna 25, the receiving antenna 31, and the amplifier 24 are housed in one casing, and that the casing has a structure that cannot be easily opened. Furthermore, here, when the electronic device 1 is installed on the stationary object 100, the transmitting antenna 25 may transmit the transmission wave T to the outside of the stationary object 100, for example, via a cover member such as a radar cover. . In this case, the radar cover may be made of a material that allows electromagnetic waves to pass through, such as synthetic resin or rubber. This radar cover may be used as a housing for the electronic device 1, for example. By covering the transmitting antenna 25 with a member such as a radar cover, it is possible to reduce the risk of the transmitting antenna 25 being damaged or malfunctioning due to contact with the outside. The radar cover and housing may also be referred to as a radome.

The electronic device 1 shown in FIG. 2 shows an example including two transmitting antennas 25. However, in one embodiment, the electronic device 1 may include any number of transmitting antennas 25. On the other hand, in one embodiment, the electronic device 1 may include a plurality of transmitting antennas 25 when transmitting waves T transmitted from the transmitting antennas 25 form a beam in a predetermined direction. In one embodiment, the electronic device 1 may include any plurality of transmitting antennas 25. In this case, the electronic device 1 may also include a plurality of phase control units 23 and a plurality of amplifiers 24 in correspondence with the plurality of transmitting antennas 25. The plurality of phase control units 23 may each control the phases of the plurality of transmission waves supplied from the synthesizer 22 and transmitted from the plurality of transmission antennas 25. Further, the plurality of amplifiers 24 may each amplify the power of the plurality of transmission signals transmitted from the plurality of transmission antennas 25. Further, in this case, the electronic device 1 may be configured to include a plurality of transmitting antennas. In this way, when the electronic device 1 shown in FIG. 2 includes a plurality of transmitting antennas 25, it is configured to include a plurality of functional units each necessary for transmitting the transmission waves T from the plurality of transmitting antennas 25. good.

The receiving antenna 31 receives the reflected wave R. The reflected wave R may be the transmitted wave T reflected by a predetermined object 200. The receiving antenna 31 may include a plurality of antennas, for example, receiving antennas 31A to 31D. The receiving antenna 31 can be configured similarly to receiving antennas used in known radar technology, so a more detailed description will be omitted. Receiving antenna 31 is connected to LNA 32. A received signal based on the reflected wave R received by the receiving antenna 31 is supplied to the LNA 32.

The electronic device 1 according to one embodiment receives a reflected wave R, which is a transmission wave T transmitted as a transmission signal (transmission chirp signal) such as a chirp signal from a plurality of reception antennas 31 and reflected by a predetermined object 200. can be received. In this way, when transmitting a transmission chirp signal as a transmission wave T, a reception signal based on a received reflected wave R is referred to as a reception chirp signal. That is, the electronic device 1 receives a received signal (for example, a received chirp signal) as a reflected wave R from the receiving antenna 31. Here, when the electronic device 1 is installed on the stationary object 100, the receiving antenna 31 may receive the reflected wave R from outside the stationary object 100, for example, via a cover member such as a radar cover. In this case, the radar cover may be made of a material that allows electromagnetic waves to pass through, such as synthetic resin or rubber. This radar cover may be used as a housing for the electronic device 1, for example. By covering the receiving antenna 31 with a member such as a radar cover, it is possible to reduce the risk that the receiving antenna 31 will be damaged or malfunction due to contact with the outside. The radar cover and housing may also be referred to as a radome.

Moreover, when the receiving antenna 31 is installed near the transmitting antenna 25, these may be included together in one electronic device 1. That is, one electronic device 1 may include, for example, at least one transmitting antenna 25 and at least one receiving antenna 31. For example, one electronic device 1 may include multiple transmitting antennas 25 and multiple receiving antennas 31. In such a case, one radar sensor may be covered with a cover member such as one radar cover, for example.

The LNA 32 amplifies the received signal based on the reflected wave R received by the receiving antenna 31 with low noise. The LNA 32 may be a low noise amplifier, and amplifies the received signal supplied from the receiving antenna 31 with low noise. The received signal amplified by the LNA 32 is supplied to a mixer 33.

The mixer 33 generates a beat signal by mixing (multiplying) the RF frequency reception signal supplied from the LNA 32 with the transmission signal supplied from the synthesizer 22. The beat signal mixed by the mixer 33 is supplied to the IF section 34.

The IF section 34 performs frequency conversion on the beat signal supplied from the mixer 33 to lower the frequency of the beat signal to an intermediate frequency (IF (Intermediate Frequency) frequency). The beat signal whose frequency has been lowered by the IF section 34 is supplied to the AD conversion section 35.

The AD conversion section 35 digitizes the analog beat signal supplied from the IF section 34. The AD converter 35 may be configured with any analog-to-digital converter (ADC). The beat signal digitized by the AD conversion section 35 is supplied to the distance FFT processing section 11 of the control section 10. When there are a plurality of receiving sections 30, each beat signal digitized by the plurality of AD conversion sections 35 may be supplied to the distance FFT processing section 11.

The distance FFT processing unit 11 of the control unit 10 shown in FIG. Perform processing to estimate distance. The distance FFT processing unit 11 may include a processing unit that performs fast Fourier transform, for example. In this case, the distance FFT processing unit 11 may be configured with any circuit or chip that performs Fast Fourier Transform (FFT) processing. Further, the distance FFT processing unit 11 may perform Fourier transform other than fast Fourier transform.

The distance FFT processing section 11 performs FFT processing on the beat signal digitized by the AD conversion section 35 (hereinafter, appropriately referred to as "distance FFT processing"). For example, the distance FFT processing section 11 may perform FFT processing on the complex signal supplied from the AD conversion section 35. The beat signal digitized by the AD converter 35 can be expressed as a time change in signal strength (power). By performing FFT processing on such a beat signal, the distance FFT processing unit 11 can express it as signal strength (power) corresponding to each frequency. By performing distance FFT processing in the distance FFT processing section 11, a complex signal corresponding to the distance can be obtained based on the beat signal digitized by the AD conversion section 35.

If the peak in the result obtained by the distance FFT processing is equal to or greater than a predetermined threshold, the distance FFT processing unit 11 may determine that the predetermined object 200 is located at a distance corresponding to the peak. For example, in detection processing using Constant False Alarm Rate (CFAR), if a peak value greater than a threshold is detected from the average power or amplitude of a disturbance signal, an object that reflects the transmitted wave (reflecting object) ) exists.

In this way, the electronic device 1 according to one embodiment targets the object 200 that reflects the transmitted wave T based on the transmitted signal transmitted as the transmitted wave T and the received signal received as the reflected wave R. can be detected. In one embodiment, the above operations may be performed by the control unit 10 of the electronic device 1.

The distance FFT processing unit 11 can estimate the distance to a predetermined object based on one chirp signal (for example, c1 shown in FIG. 3). That is, the electronic device 1 can measure (estimate) the distance L shown in FIG. 1 by performing distance FFT processing. Since the technique itself for measuring (estimating) the distance to a predetermined object by performing FFT processing on the beat signal is well known, a more detailed explanation will be simplified or omitted as appropriate. The results of the distance FFT processing performed by the distance FFT processing section 11 (for example, distance information) may be supplied to the speed FFT processing section 12 . Further, the results of the distance FFT processing performed by the distance FFT processing section 11 may be supplied to the subsequent determination section 16, angle of arrival estimation section 17, and/or object detection section 18, etc.

The speed FFT processing unit 12 performs processing for estimating the relative speed between the stationary object 100 carrying the electronic device 1 and the object 200 based on the beat signal subjected to the distance FFT processing by the distance FFT processing unit 11. conduct. The velocity FFT processing unit 12 may include, for example, a processing unit that performs fast Fourier transform. In this case, the velocity FFT processing section 12 may be configured with any circuit or chip that performs Fast Fourier Transform (FFT) processing. The velocity FFT processing unit 12 may perform Fourier transform other than fast Fourier transform.

The speed FFT processing section 12 further performs FFT processing on the beat signal that has been subjected to the distance FFT processing by the distance FFT processing section 11 (hereinafter, appropriately referred to as "velocity FFT processing"). For example, the velocity FFT processing section 12 may perform FFT processing on the complex signal supplied from the distance FFT processing section 11. The velocity FFT processing unit 12 can estimate the relative velocity with respect to a predetermined object based on a subframe of the chirp signal (for example, subframe 1 shown in FIG. 3). By performing speed FFT processing on a plurality of chirp signals in the speed FFT processing section 12, a complex signal corresponding to the relative velocity is obtained based on the complex signal corresponding to the distance obtained by the distance FFT processing section 11.

By performing distance FFT processing on the beat signal as described above, a plurality of vectors can be generated. By calculating the phase of the peak in the results of performing velocity FFT processing on these plurality of vectors, the relative velocity with respect to a predetermined object can be estimated. That is, the electronic device 1 can measure (estimate) the relative speed between the stationary object 100 and the predetermined object 200 shown in FIG. 1 by performing speed FFT processing. The technique itself for measuring (estimated) the relative velocity with a predetermined object by performing velocity FFT processing on the results of distance FFT processing is well known, so a more detailed explanation will be simplified or omitted as appropriate. do. The result of the speed FFT processing performed by the speed FFT processing section 12 (for example, speed information) may be supplied to the arrival angle estimating section 17 . Further, the result of the speed FFT processing performed by the speed FFT processing section 12 may be supplied to the determination section 16 and/or the object detection section 18 in the subsequent stage.

Further, when the speed FFT processing unit 12 performs speed FFT processing, window control may be applied to prevent discontinuity points from occurring. In that case, the velocity FFT processing unit 12 does not have to output the relative velocity adjacent to the relative velocity of the stationary object.

The difference calculation unit 13 stores, in the storage unit 14, the signal intensity corresponding to the distance of the area where the relative velocity with respect to the electronic device 1 is zero (ie, the area of a stationary object). Here, the signal strength may indicate the power or amplitude of the received signal. When calculating the difference data, the difference calculation unit 13 may store the distribution of signal intensity corresponding to the distance of the stationary object region in the storage unit 14.

The storage unit 14 may store programs executed by the control unit 10 or each functional unit of the control unit 10, results of processing executed by the control unit 10, and the like. Furthermore, the storage unit 14 may function as a work memory for the control unit 10. The storage unit 14 can be configured by, for example, a semiconductor memory or a magnetic disk, but is not limited thereto, and can be any storage device. Further, for example, the storage unit 14 may be a storage medium such as a memory card inserted into the electronic device 1 according to the present embodiment. Further, the storage unit 14 may be an internal memory of the CPU used as the control unit 10, as described above. The storage unit 14 may also serve as any of the above-mentioned storage units.

The difference calculation unit 13 may average the signal strength (power or amplitude) corresponding to the distance of the stationary object region stored in the storage unit 14 over a plurality of different times.

As described above, the difference calculation unit 13 performs distance FFT processing and velocity FFT processing on the beat signal received in the frame of the transmission wave as described above. Then, the difference calculation unit 13 calculates the difference between the distribution of signal strength (power or amplitude) corresponding to the distance of the stationary object and the distribution of signal strength corresponding to the distance of the relative velocity of the stationary object stored in the storage unit 14. Calculate.

On the other hand, the difference calculation unit 13 may not calculate the difference in signal strength corresponding to the distance of an area where the relative velocity with respect to the electronic device 1 is not zero (that is, an area that is not a stationary object). The signal strength of the complex signal corresponding to the distance when calculating the difference may be smoothed by using a moving average of a plurality of different times, for example, a moving average between frames of transmitted waves.

The update processing unit 15 updates the difference data used by the difference calculation unit 13 as necessary. For example, if the correlation value of difference data acquired at two or more different times in the difference data stored in the storage unit 14 is greater than or equal to the threshold value, the update processing unit 15 determines that there is no change in the environment of the stationary object. Then, the difference data may be updated. Furthermore, when updating the difference data, the update processing unit 15 may acquire data at different times several times and adopt data that remains unchanged.

The determination unit 16 determines the distance and/or relative speed based on the result of the distance FFT process performed by the distance FFT process unit 11 and/or the result of the speed FFT process performed by the speed FFT process unit 12. Perform judgment processing. The determination unit 16 determines whether an object is detected at a predetermined distance and/or a predetermined relative speed. The determination by the determination unit 16 will be further explained below.

In general FM-CW radar technology, it is possible to determine whether or not a target exists based on the result of performing fast Fourier transform processing on the beat frequency extracted from the received signal. Here, the result of extracting the beat frequency from the received signal and performing fast Fourier transform processing includes noise components such as clutter (unnecessary reflection components). Therefore, processing may be performed to remove noise components from the result of processing the received signal and extract only the target signal.

As a method for determining whether or not a target exists, there is a method in which a threshold is set for the output of a received signal and the target is deemed to be present when the intensity of the reflected signal exceeds the threshold (threshold detection method). If this method is adopted, even if the signal strength of clutter exceeds the threshold, it will be determined that it is a target, and a so-called "false alarm" will be issued. Whether or not the signal strength of this clutter exceeds a threshold is determined by statistical probabilities. The probability that the signal strength of this clutter exceeds the threshold is called the "false alarm probability." A constant false alarm rate can be used as a method to keep the false alarm probability low and constant.

Hereinafter, Constant False Alarm Rate will also be simply referred to as CFAR. In CFAR, the assumption is used that the signal strength (amplitude) of noise follows a Rayleigh distribution. Based on this assumption, if the weights used to calculate the threshold used to determine whether a target is detected are fixed, the target detection error rate will theoretically remain constant regardless of the noise amplitude. .

As a CFAR in general radar technology, a method called Cell Averaging CFAR (hereinafter also referred to as CA-CFAR) is known. In CA-CFAR, signal strength values (for example, amplitude values) of received signals that have been subjected to predetermined processing may be sequentially input to a shift register at regular sampling intervals. This shift register has a test cell (cell under test) in the center, and a plurality of reference cells (reference cells) on each side of the test cell. Each time a signal strength value is entered into the shift register, the previously entered signal strength value is transferred from one end of the shift register (e.g., the left end) to the other end (e.g., the right end) of the cell, one by one. are moved by. Further, each value of the reference cell is averaged in synchronization with the input timing. The average value obtained in this way is multiplied by a prescribed weight and calculated as a threshold value. If the value of the test cell is larger than the threshold value calculated in this manner, the value of the test cell is output as is. On the other hand, if the value of the test cell is not larger than the calculated threshold value, a 0 (zero) value is output. In this way, in CA-CFAR, a detection result can be obtained by calculating a threshold value from the average value of reference cells and determining whether or not a target exists.

In CA-CFAR, for example, when a plurality of targets are located close to each other, the threshold value calculated in the vicinity of the target becomes large due to the nature of the algorithm. Therefore, some targets may not be detected even though they have sufficient signal strength. Similarly, when there is a clutter level difference, the threshold value calculated near the clutter level difference also increases. In this case as well, small targets near the clutter step may not be detected.

In contrast to CA-CFAR described above, Order Statistic CFAR (hereinafter referred to as There is a method called OS-CFAR). OS-CFER is a method that sets a threshold based on ordered statistics and determines that a target exists when the threshold is exceeded. According to this OS-CFAR, the problems in CA-CFAR as described above can be addressed. OS-CFAR can be realized by performing processing that is partially different from CA-CFAR. Hereinafter, a description will be given assuming that the electronic device 1 according to one embodiment executes OS-CFAR processing.

The determination unit 16 may determine object detection using OS-CFAR. In this case, the determination unit 16 may perform the determination using different threshold values in the area of a stationary object and the area of a non-stationary object. Further, when performing the window control described above, the determination unit 16 may not detect a region of relative velocity adjacent to a stationary object. The determination unit 16 may use regions with the same relative velocity but different distances as noise regions used in OS-CFAR.

The angle of arrival estimation unit 17 estimates the direction (angle of arrival) in which the reflected wave R arrives from the predetermined object 200 based on the result of the determination by the determination unit 16. The angle of arrival estimating unit 17 may estimate the angle of arrival for the points determined by the determining unit 16 to satisfy the threshold. By receiving the reflected waves R from the plurality of reception antennas 31, the electronic device 1 can estimate the direction in which the reflected waves R arrive. For example, it is assumed that the plurality of receiving antennas 31 are arranged at predetermined intervals. In this case, a transmission wave T transmitted from the transmission antenna 25 is reflected by a predetermined object 200 and becomes a reflected wave R, and each of the plurality of reception antennas 31 arranged at a predetermined interval receives the reflected wave R. Then, the arrival angle estimation unit 17 estimates the direction in which the reflected wave R arrives at the receiving antenna 31 based on the phase of the reflected wave R received by each of the plurality of receiving antennas 31 and the path difference of each reflected wave R. can do. That is, the electronic device 1 can measure (estimate) the arrival angle θ shown in FIG. 1 based on the result of the speed FFT process.

Various techniques have been proposed for estimating the direction in which the reflected wave R arrives based on the results of velocity FFT processing. For example, known direction-of-arrival estimation algorithms include MUSIC (MUltiple SIgnal Classification) and ESPRIT (Estimation of Signal Parameters via Rotational Invariance Technique). Therefore, more detailed descriptions of well-known techniques will be simplified or omitted where appropriate. Information on the angle of arrival θ (angle information) estimated by the angle of arrival estimation unit 17 may be supplied to the object detection unit 18.

The object detection unit 18 detects objects existing in the range where the transmission wave T is transmitted based on information supplied from at least one of the distance FFT processing unit 11, the velocity FFT processing unit 12, and the angle of arrival estimation unit 17. To detect. The object detection unit 18 may perform object detection by performing, for example, clustering processing based on the supplied distance information, speed information, and angle information. As an algorithm used when clustering data, for example, DBSCAN (Density-based spatial clustering of applications with noise) is known. In the clustering process, for example, the average power of points forming the detected object may be calculated. The distance information, speed information, angle information, and power information of the object detected by the object detection unit 18 may be supplied to other devices, for example. The object detection unit 18 may calculate the average power of the point group that constitutes the object.

The electronic device 1 shown in FIG. 2 includes two transmitting antennas 25 and four receiving antennas 31. However, the electronic device 1 according to one embodiment may include an arbitrary number of transmitting antennas 25 and an arbitrary number of receiving antennas 31. For example, by including the two transmitting antennas 25 and the four receiving antennas 31, the electronic device 1 can be considered to include a virtual antenna array virtually configured with eight antennas. In this way, the electronic device 1 may receive the reflected waves R of the 16 subframes shown in FIG. 4 by using, for example, eight virtual antennas.

Next, the operation of the electronic device 1 according to one embodiment will be described.

FIG. 5 is a flowchart illustrating operations performed by the electronic device 1. The flow of operations performed by the electronic device 1 will be schematically explained below. The operation shown in FIG. 5 may be started, for example, when the electronic device 1 attached to the stationary object 100 detects an object existing around the stationary object 100.

When the process shown in FIG. 5 starts, the control unit 10 controls the transmission antenna 25 of the electronic device 1 to transmit a transmission wave (step S11).

When the transmission wave is transmitted in step S11, the control unit 10 controls the reception antenna 31 of the electronic device 1 to receive a reflected wave from the transmission wave reflected by an object (step S12).

When the reflected wave is received in step S12, the control unit 10 performs distance FFT processing and velocity FFT processing on the beat signal based on the transmitted wave and the reflected wave (step S13). In step S13, the distance FFT processing unit 11 may perform distance FFT processing, and the velocity FFT processing unit 12 may perform velocity FFT processing.

After the distance FFT process and the velocity FFT process are performed in step S3, the difference calculation unit 13 determines whether the relative speed between the electronic device 1 and the object is zero (step S14). If the relative velocity is not zero in step S14, the process shown in FIG. 5 may be terminated.
Furthermore, if the relative velocity is not zero in step S14, object detection may be determined using a different threshold value than in the case of a stationary object, as described above.

If the relative velocity is zero in step S14, the difference calculation unit 13 stores the signal strength (power or amplitude) of the complex signal corresponding to the distance in the storage unit 14 (step S15).

After the signal strength of the complex signal corresponding to the distance is stored in step S15, the difference calculation unit 13 performs the process of step S16. In step S16, the difference calculation unit 13 calculates the difference between the signal strength corresponding to a distance of a stationary object whose relative velocity is zero, and the signal strength stored in the storage unit 14.

Once the difference is calculated in step S16, the determination unit 16 determines whether the difference exceeds a predetermined threshold (step S17). If the difference does not exceed the threshold in step 17, the control unit 10 may end the operation shown in FIG. 5. In this case, object detection by OS-CFAR may not be performed for differences that do not exceed the threshold.

If the difference exceeds the threshold in step 17, the object detection unit 18 performs object detection using OS-CFAR. The operation shown in FIG. 5 may be repeatedly executed, for example, at a predetermined timing or irregularly.

According to the electronic device 1 according to one embodiment, after fast Fourier transform of distance and velocity, a difference corresponding to the relative velocity of a stationary object is calculated. Therefore, according to the electronic device 1, it is possible to detect a stationary object with a low reflectance even in an environment where there are highly reflective objects around the stationary object, for example. Further, according to the electronic device 1, a moving object can also be detected by performing dynamic detection using different threshold values. Therefore, according to the electronic device 1 according to one embodiment, objects can be detected satisfactorily.

FIG. 6 is a diagram showing an example of the distribution of power with respect to distance and speed after performing conventional distance FFT processing and speed FFT processing in order to compare with the effect of the electronic device 1 according to an embodiment. As shown in FIG. 2, it can be seen that the distribution of signal strength (amplitude) with respect to distance becomes large when the relative velocity is zero (ie, a stationary object).

FIG. 7 is a diagram illustrating an example of detection by the electronic device 1 according to an embodiment. FIG. 7 shows an example of a result of detecting an object by the electronic device 1 when the object is placed around the electronic device 1 according to an embodiment. FIG. 7 shows the power distribution with respect to distance and speed for the result of subtracting the difference data of a stationary object whose relative speed is zero. As shown in FIG. 7, it can be seen that according to the electronic device 1 according to the embodiment, a peak occurs only in the detected object.

Although the present disclosure has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various changes or modifications based on the present disclosure. It should therefore be noted that these variations or modifications are included within the scope of this disclosure. For example, functions included in each functional unit can be rearranged so as not to be logically contradictory. A plurality of functional units etc. may be combined into one or may be divided. Each of the embodiments according to the present disclosure described above is not limited to being implemented faithfully to each described embodiment, but may be implemented by combining each feature or omitting a part as appropriate. . In other words, those skilled in the art can make various changes and modifications to the content of the present disclosure based on the present disclosure. Accordingly, these variations and modifications are included within the scope of this disclosure. For example, in each embodiment, each functional unit, each means, each step, etc. may be added to other embodiments so as not to be logically contradictory, or each functional unit, each means, each step, etc. of other embodiments may be added to other embodiments to avoid logical contradiction. It is possible to replace it with Furthermore, in each embodiment, a plurality of functional units, means, steps, etc. can be combined into one or divided. Furthermore, the embodiments of the present disclosure described above are not limited to being implemented faithfully to each of the described embodiments, but may be implemented by combining features or omitting some features as appropriate. You can also do that.

The embodiment described above is not limited to implementation as the electronic device 1. For example, the embodiment described above may be implemented as a method of controlling a device such as the electronic device 1. Furthermore, for example, the embodiment described above may be implemented as a program executed by a device such as the electronic device 1.

1 Electronic equipment 10 Control section 11 Distance FFT processing section 12 Speed FFT processing section 13 Difference calculation section 14 Storage section 15 Update processing section 16 Judgment section 17 Arrival angle estimation section 18 Object detection section 20 Transmission section 21 Signal generation section 22 Synthesizer 23 Phase Control section 24 Amplifier 25 Transmission antenna 30 Receiving section 31 Receiving antenna 32 LNA
33 Mixer 34 IF section 35 AD conversion section

Claims (3)

An electronic device stationary relative to the ground that detects an object based on a transmission wave transmitted from a transmission antenna and a reflected wave from the transmission wave reflected by the object,
From the reflected wave,
Regarding the first area that is stationary with respect to the ground, the signal intensity corresponding to the distance of the first area and the pre-calculated distance of the area of the stationary object that is stationary with respect to the ground Detecting an object in the first region based on the difference with the corresponding signal strength,
For the second area that is not stationary with respect to the ground, the signal intensity corresponding to the distance of the second area and the pre-calculated distance of the area of the stationary object that is stationary with respect to the ground. An electronic device that detects an object in the second region without calculating a difference between the signal strength and the signal intensity corresponding to the second region . A method for controlling electronic equipment that is stationary with respect to the ground,
Detecting the object based on a transmitted wave transmitted from a transmitting antenna and a reflected wave resulting from the transmitted wave being reflected by the object,
The detecting step includes:
From the reflected wave,
Regarding the first area that is stationary with respect to the ground, the signal intensity corresponding to the distance of the first area and the pre-calculated distance of the area of the stationary object that is stationary with respect to the ground Detecting an object in the first region based on the difference with the corresponding signal strength,
For the second area that is not stationary with respect to the ground, the signal intensity corresponding to the distance of the second area and the pre-calculated distance of the area of the stationary object that is stationary with respect to the ground. A control method for detecting an object in the second region without calculating a difference between the signal strength and the signal strength corresponding to the second region . For electronic devices that are stationary relative to the ground,
A program that executes a step of detecting an object based on a transmission wave transmitted from a transmission antenna and a reflected wave resulting from the transmission wave being reflected by an object, the program comprising:
The detecting step includes:
From the reflected wave,
Regarding the first area that is stationary with respect to the ground, the signal intensity corresponding to the distance of the first area and the pre-calculated distance of the area of the stationary object that is stationary with respect to the ground Detecting an object in the first region based on the difference with the corresponding signal strength,
For the second area that is not stationary with respect to the ground, the signal strength corresponding to the distance of the second area and the pre-calculated distance of the area of the stationary object that is stationary with respect to the ground A program that detects an object in the second region without calculating a difference between the signal strength and the signal intensity corresponding to the second region .

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